1. Field of the Invention
The present invention relates to a vacuum interrupter, and particularly, to an electrode for a vacuum interrupter.
2. Background of the Invention
A vacuum interrupter refers to a power system used as a main circuit switching mechanism for a circuit breaker of a high voltage corresponding to several kilo voltages, or a main circuit switching mechanism of a super high voltage corresponding to several tens or hundreds of voltages, due to a high electric insulation characteristic and an arc extinguishing function in a vacuum state.
A structure and an operation of a general vacuum interrupter will be explained with reference to FIG. 1.
A vacuum interrupter 100 comprises an insulating container 60 maintaining a vacuum state and formed of an electric insulating material such as ceramic; a fixed electrode 10 fixedly installed in the insulating container 60; and a movable electrode 40 configured to be movable to a closing position contacting the fixed electrode 10, or an opening position separated from the fixed electrode 10. The fixed electrode 10 is connected to a fixed rod 20 connected to a power source of an electric circuit. The fixed rod 20 has a part extending to inside of the insulating container 60 thus to be connected to the fixed electrode 10, and a part extending to outside of the insulating container 60 thus to be connected to the power side.
A movable electrode 40 is connected to a movable rod 30 connected to an electrical load of the electric circuit. The movable rod 30 has a part extending to inside of the insulating container 60 thus to be connected to the movable electrode 40, and a part extending to outside of the insulating container 60 thus to be connected to the load side.
At an inner center of the insulating container 60, installed is a central arc shield 70 for shielding an inner wall of the insulating container 60 from an arc generated when the movable electrode 40 is moved to an opening position separated from the fixed electrode 10.
Connection flanges 60a and 60b are welded to outer upper and lower parts of the insulating container 60, respectively, thereby maintaining the inside of the insulating container 60 as a hermetic state.
The connection flange 60b disposed at a lower part of the insulating container 60 is provided with a guide flange 90 for allowing the movable rod 30 to be movable in an axial direction.
A bellows 50 is connected to the lower connection flange 60b adjacent to the movable rod 30, so as to be expanded or contracted as the movable rod 30 moves. And, a bellows shielding member 80 for shielding the bellows 50 from an arc is installed so as to shield the end of the bellows 50, the end disposed at a side of the movable electrode 40.
In order to rapidly extinguish an arc generated between the movable electrode and the fixed electrode of the vacuum interrupter when the movable electrode moves to an open circuit position, has been proposed a structure to generate an axial magnetic flux (AMF).
However, in the conventional electrode, an axial magnetic flux (AMF) density is increased at the center of the electrode. This phenomenon causes an arc to be concentrated to the center of the electrode, resulting in high heat emission. As a result, the centers of the contacts in the movable electrode and the fixed electrode may be damaged.
Furthermore, since an arc is concentrated to the center of the electrode, it may take a long time to extinguish the arc.